CHEMICALLY TREATED ANIMAL FIBER MATRIX PLANT CULTIVATION COMPOSITION

Abstract

A soil-less plant cultivation substrate, for use in hydroponic or aeroponic plant cultivation, adapts entangled layers of natural wool batting that has been chemically treated with a compound containing thiol to increase its water holding capacity. In the preferred embodiment, the chemical treatment uses thioglycolic acid, such as calcium thioglycolate or ammonium thioglycolate, to increase the wool's solubility and then a neutralizing agent, such as hydrogen peroxide, halts the process. The thiol compound reduces the disulfide bonds of cysteine in the cortex of the wool and the hydrogen peroxide neutralizes the reaction and oxidizes the cysteines back to cystine, although not all disulfide bonds are reformed. The addition of an alkaline modifier is used to moderate or hasten the breaking the disulfide bonds.

Claims

1. A plant growth substrate comprising at least 70% by weight animal derived wool, wherein the animal derived wool is chemically treated with a compound containing thiol.

2. The plant growth substrate of claim 1 wherein the compound containing thiol is a thioglycolic acid.

3. The plant growth substrate of claim 2 wherein the thioglycolate acid is a salt of thioglycolic acid.

4. The plant growth substrate of claim 3 wherein the salt of thioglycolic acid is selected group consisting of ammonium thioglycolate, calcium thioglycolate, potassium thioglycolate, and sodium thioglycolate.

5. The plant growth substrate of claim 2 wherein the wool is chemically treated by submerging the wool in an aqueous solution containing the thioglycolic acid.

6. The plant growth substrate of claim 5 wherein the aqueous solution contains between 1% and 20% by weight of the thioglycolic acid and between 0.02% and 1.5% of an alkaline substance.

7. The plant growth substrate of claim 6 wherein the alkaline substance is selected from the group consisting of calcium hydroxide, sodium hydroxide, potassium hydroxide, or ammonium hydroxide.

8. The plant growth substrate of claim 7 wherein the aqueous solution contains 8% by weight of thioglycolic acid and 0.75% by weight of the alkaline substance.

9. The plant growth substrate of claim 2 wherein the wool is chemically treated by enclosing the wool in a gaseous environment containing the thioglycolic acid.

10. The plant growth substrate of claim 9 wherein the wool is enclosed in the gaseous environment under pressure above atmosphere.

11. The plant growth substrate of claim 1 wherein the animal derived wool is from sheep, goat, alpaca or llama.

12. The plant growth substrate of claim 1 wherein the animal derived wool is formed into a felt bat.

13. The plant growth substrate of claim 12 wherein the felt bat is formed into at least two felt bat layers and the at least two felt bat layers are layered one atop another.

14. The plant growth substrate of claim 13 wherein the at least two felt bat layers are needle punched to entangle the wool fibers between the at least two felt bat layers.

15. The plant growth substrate of claim 14 wherein the substrate has a horizontal orientation and the wool fibers entangled between the at least two felt bat layers form wool fibers oriented in a vertical direction with respect to the horizontal orientation of the substrate.

16. The plant growth substrate of claim 15 wherein the at least two felt bat layers form a height between 0.5 cm and 30 cm.

17. The plant growth substrate of claim 1 wherein a plant is cultivated within the substrate hydroponically.

18. The plant growth substrate of claim 1 wherein a plant is cultivated within the substrate aeroponically.

19. The plant growth substrate of claim 14 further comprising a reinforcing fabric between the at least two felt bat layers to adapt the plant growth substrate.

Description

4. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1 is a three-quarter perspective view of the chemically treated animal fiber matrix plant substrate of the present invention.

[0021] FIG. 2A is a side cross-section view of the chemically treated animal fiber matrix plant bats being subjected to barbed needle punching.

[0022] FIG. 2B is a close-up side cross-section view of the chemically treated animal fiber matrix plant bats being subjected to barbed needle punching.

[0023] FIG. 3 is a three-quarter exploded perspective view of the layers of the chemically treated animal fiber and synthetic fiber mesh geofabric interposed between them.

[0024] FIG. 4 is a side cross-section view of the chemically treated animal fiber matrix plant substrate of the present invention immersed in an hydroponic growth tray.

5. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention features a fibrous mat matrix 10 comprised primarily of animal wool fibers in layers 15 of battings, also referred to as bats, mechanically bonded, as described below. The wool of the bat layers is chemically treated with a compound containing thiol. The chemical treatment of clean wool fiber may be performed either prior to or after the felting process. A preferred chemical is thioglycolic acid in the form of ammonium thioglycolate, which increases its solubility. The keratin molecules in the wool fibers are arranged in straight bundles held together by disulphide bonds. The disulphide bonds are made by the cysteine amino acid. The cysteine of one keratin molecule forms a disulphide bond with the cysteine of the neighboring keratin molecule Ammonium thioglycolate (HSCH.sub.2CO.sub.2NH.sub.4), which contains a thiol group (—SH), breaks the disulphide bonds. The thiol group replaces one of the sulphur atoms in the disulphide bond:

Keratin-S—S-keratin+2HS—CH.sub.2CO.sub.2NH.sub.4.fwdarw.—HO.sub.2CH.sub.2CS-SCH.sub.2CO.sub.2H+2NH.sub.3+2HS-keratin

When the disulphide bond is broken, the keratin bundles come apart, which increases the water holding capacity of the keratin fibers. The thiol compound is allowed to work on the wool fibers.

[0026] The thiol containing compounds work best at reducing the disulfide bonds of cysteine in the cortex of wool and, as discussed below, a hydrogen peroxide treatment neutralizes the reaction and oxidizes the cysteines (HO.sub.2CCHCH.sub.2SH) back to cystine, but not all disulfide bonds are reformed. Numerous chemicals were tested to digest the keratin partially, as the keratin protein resists degradation. The addition of an alkaline substance, preferably calcium hydroxide (Ca(OH).sub.2), is used as a pH modifier to moderate or hasten the reaction of breaking the disulfide bonds. Alternative choices for a pH modifier are sodium hydroxide (NaOH), potassium hydroxide (KOH), and ammonium hydroxide (NH.sub.4OH).

[0027] The chemical treatment may be carried out as follows: [0028] 1. For 100 grams (dry weight) of clean wool, saturate the wool with distilled water and allow to soak for 5 minutes. Remove excess water by manual squeezing until no more water flows from the wool. [0029] 2. Expose the clean, wet wool with 50 grams of an aqueous solution containing between 1% and 20% by weight of thioglycolic acid and between 0.02% to 1.5% an alkaline substance, such as ammonium hydroxide, calcium hydroxide, potassium hydroxide, or sodium hydroxide. In the preferred proportions, the clean, wet wool is exposed to an aqueous solution containing 8% by weight thioglycolic acid and 0.75% ammonium hydroxide for 45 minutes. The higher the percent of thioglycolic acid, the more rapid is the reaction of breaking disulfide bridges in the keratin. The ammonium hydroxide acts as a pH modifier by raising the alkalinity of the solution. The ammonium hydroxide, when ammonia is dissolved in water, also acts on the wool fiber, causing it to swell, which facilitates the action of the thioglycolic acid. [0030] 3. Rinse the treated wool with distilled water for 5 minutes. [0031] 4. Expose the treated wool to an aqueous solution containing up to 3.0% hydrogen peroxide for 5 minutes. Higher amounts of thioglycolic acid require more hydrogen peroxide for the neutralization step, but the amount of hydrogen peroxide should not exceed 3.0%. [0032] 5. Rinse the treated wool thoroughly for 5 minutes with distilled water. Manually squeeze and allow to dry.

[0033] If heat is applied or the percent by weight of the thioglycolic acid is increased during step 2, the chemical reaction on the wool is hastened. The pH of the thioglycolic solution also impacts the breaking of the disulfide bridges. The best results occurred in the pH range from 7.0 to 10.0.

[0034] For course wool, with an average size of about 22 microns, continuous sheets or needle-felted bats of wool can be submerged in a thiol containing aqueous environment for about 45 minutes at room temperature (approximately 70° Fahrenheit). Course wool is a good choice for the substrate, since it is most often regarded as a waste byproduct of wool production, available in large quantities, and inexpensive. The treatment time is affected by temperature. At higher temperatures, the treatment time should be reduced. For finer wool, treatment requires less time.

[0035] Alternatively, the thiol containing compound and pH modifier may be applied to the natural wool in a gaseous environment under heat, pressure, or both. In a gas treatment, some of the active ingredients may be more easily recovered for reuse.

[0036] Following treatment with the thiol containing compound, the wool is compressed to squeeze the solution from the wool and then rinsed in water.

[0037] Once the thiol compound treatment has been completed, the remaining thiol compound in the wool is neutralized with an oxidation solution containing hydrogen peroxide (H.sub.2O.sub.2), which reconstitutes the disulphide bonds:

2Keratin-SH+H.sub.2O.sub.2.fwdarw.Keratin-S—S-keratin+2H.sub.2O

[0038] The treatment produces wool fibers that are slightly acidic, with a pH of approximately 5.5 to 6.0, ideal for plant growth.

[0039] The chemical treatment described above can be applied to wool that has been cleaned, prior to picking, carding, or needle punching.

[0040] Once the wool has been treated, it may be formed into a mat matrix for plant cultivation. In a preferred embodiment, the fibers are blended and carded to form bats or webs 15. The wool fibers in these bats 15 are aligned in a direction, 16 and 17, generally parallel to the mat, that is, horizontally. The bats 15 are then layered one on top of another with fiber directions, 16 or 17, transverse to each other or in an orientation between normal. The bat layers 15 are then mechanically needled (as in FIGS. 2A and 2B), whereby the bat 15 is punched and the fibers, 16 and 17, of the layers 15 are tangled by a multiplicity of barbed 32 felting needles 31. Needling can be accomplished by either a one-sided loom employing either a down stroke or an up stroke or by a double sided needle loom with or without pre-needling, commonly known as a tacker. In one preferred embodiment, several bats are needled together in multiple passes through the tacker or needle loom, producing a thicker mat of more homogeneous fiber entanglement.

[0041] In alternative embodiment, the wool fibers are formed into bats by the use of air laid fibers onto a receiving platen or belt, thereby forming a randomly arranged fiber bat, which is subsequently needled forming the final fiber entangled mat.

[0042] The cohesive mat matrix is cut into predetermined shapes, such as a cube 10 or other suitable shape. A slit 12 may be cut into the matrix substrate 10 for insertion of a seed or seedling. The slit 12 allows the roots to penetrate the substrate 10 and the plant 13 to grow outwardly.

[0043] In a preferred embodiment, the cohesive mat matrix substrate is cut into plugs 10 wherein the seedling or cutting 13 can be cultivated in the plug 10 to the point of transplant age or size and thereafter transferred to a soil or soil-less medium for continued cultivation without the damage to root tissue typically encountered in standard transplanting practice. As shown in FIG. 4, such a plug 10 is shown in a hydroponic tray 20 filled with a growth solution 21. FIG. 4 shows the plant growth substrate 10 with a plant 13 cultivated hydroponically, but may also applied to aeroponically cultivation.

[0044] The plant growth substrate 10 is formed of a cohesive matrix mat 11 of animal derived wool. The wool matrix 11 is comprised of at least 70 percent natural wool by weight. The wool fiber of the matrix 11 mat may be formed from wool from sheep, goat, alpaca, llama, or other related wool-producing species. Any remaining mixture of the wool matrix 11 may comprise organic fibers, synthetic material or a combination of organic fibers and synthetic material. The organic fibers may be, for example, cotton, jute, line, or hemp. The synthetic materials may be, for example, polyester, polyethylene, polypropylene, polyethylene terephthalate, acrylic, nylon, or olefin.

[0045] In alternative embodiment, shown in FIG. 4, a synthetic fiber mesh geofabric 19 is interposed between the layers 15 of the fiber matrix 10′ for the purpose of increasing resistance to deformation in order to adapt it for use in a green wall or green roof plant cultivation system. The reinforcing fabric layer 19, which may be natural or synthetic material, is incorporated within the natural animal wool layers 15 of a reinforced cohesive matrix 10′. When the natural animal wool layers 15 and reinforcing fabric layer 19 (or layers) are needled to entangle the wool fibers, the reinforced cohesive matrix 10′ may be used in a vertical or horizontal position, or a transition between said positions, for use as a “green roof” or “green wall” plant anchoring system.

[0046] The cohesive matrix 11 should have a density of 0:08 to 0.45 grams per cubic centimeter. The cohesive matrix 11 will comprise fibers of 7 to 50 microns in diameter and cut lengths of about 0.5 to 13 cm. A typical hydroponic plant growth substrate 10 will be in the form of a continuous mat, cut to a predetermined shape, with a thickness of from 0.2 to 30 cm. The wool and fibers of cohesive matrix 11 are randomly-arranged and entangled. Preferably, the wool and fibers of the cohesive matrix 11 are needled to form a tangled mat with a relatively vertically-aligned matrix, which promotes healthy natural root growth.

[0047] The cohesive matrix 11 mat may be formed from virgin or recycled wool, organic fibers, or synthetic material. The wool, organic fibers, or synthetic material may be dyed or pigmented.

[0048] The drawings and description set forth here represent only some embodiments of the invention. After considering these, skilled persons will understand that there are many ways to make a chemically treated animal fiber matrix plant cultivation composition according to the principles disclosed. The inventor contemplates that the use of alternative structures, materials, or manufacturing techniques, which result in a chemically treated animal fiber matrix plant cultivation composition according to the principles disclosed, will be within the scope of the invention.